1. Field of the Invention
The present invention relates to a grinding machine of the type in which raw material to be ground is agitated in the presence of a large number of grinding media and more particularly to improvement of a grinding machine of the above-mentioned type.
2. Description of the Prior Art
There is already known a media agitating type grinding machine which is so constructed that a rotational shaft with a number of agitating rods fitted thereto is extended through a grinding tank which is installed in the horizontal posture and grinding is achieved under the effect of agitation of the agitating rods while raw material to be ground is mixed with the media as the rotational shaft is rotated. Since it is found that this type of grinding machine consumes less power than conventional ball mill or the like, the former has been widely put in practical use in many industrial fields.
As mentioned above, the media agitating type grinding machine has wide application fields which have increased year by year but it is pointed out as a drawback inherent to the grinding machine that when raw material having high adhesiveness is ground, it tends to be adhesively deposited on the inner wall of a raw material inlet port. To obviate the drawback there was proposed a grinding machine which was equipped with a breaker at the inlet port. To facilitate understanding of the present invention it will be helpful that the proposed grinding machine will be described below with reference to FIGS. 2 and 3.
FIG. 2 is a fragmental vertical sectional view of the grinding machine, particularly illustrating how the inlet port is constructed and FIG. 3 is a plan view of the grinding machine in FIG. 2. A pneumatical cylinder 28 is pivotally mounted on a bracket 30 with the aid of a trunion 29. A piston 31 extends forwardly of the pneumatical cylinder 28 and carries an arm 25 at the foremost end thereof with the use of a pin 24 while the lowermost end of the arm 25 is operatively connected to a shaft 26. As will be best seen in FIG. 3, the shaft 26 extends across the inlet port in the horizontal direction and a breaker 27 is turnably mounted on the shaft 26.
As the pneumatical cylinder 28 is operated, the piston 31 is reciprocably displaced and thereby the breaker 27 is caused to turn in both the directions as identified by arrow marks in FIG. 2, resulting in raw material deposited on the inner wall of the inlet port being removed therefrom.
However, it is found that the proposed grinding machine has another drawback that an effective working space is reduced due to existence of the breaker and unexpectedly this leads to promotion of deposition of raw material on the inner wall of the inlet port. Further, since the breaker 27 is caused to turn about the central shaft 26, it results that raw material deposited in the corner area of the inlet port cannot be completely removed. Moreover, due to the fact that the shaft 26 should be mounted in such a manner as to extend through both the side walls of the inlet port there is a necessity for gastightly sealing the parts of the side walls through which the shaft 26 extends.